[PATCH v4 1/3] watchdog: aspeed: Update bootstatus handling

[Guenter Roeck]

On 11/1/24 05:11, Chin-Ting Kuo wrote:
> The boot status in the watchdog device struct is updated during
> controller probe stage. Application layer can get the boot status
> through the command, cat /sys/class/watchdog/watchdogX/bootstatus.
> 
> The boot status mapping rule follows the latest design guide from
> the OpenBMC shown as below.
> https://github.com/openbmc/docs/blob/master/designs/bmc-reboot-cause-update.md#proposed-design
> - WDIOF_EXTERN1   => system is reset by Software
> - WDIOF_CARDRESET => system is reset by WDT SoC reset
> - Others          => other reset events, e.g., power on reset.
> 
> On ASPEED platform, the boot status is recorded in the SCU registers.
> - AST2400: Only a bit represents for any WDT reset.
> - AST2500: The reset triggered by different WDT controllers can be
>             distinguished by different SCU bits. But, WDIOF_EXTERN1 or
>             WDIOF_CARDRESET still cannot be identified due to
>             HW limitation.
> - AST2600: Different from AST2500, additional HW bits are added for
>             distinguishing WDIOF_EXTERN1 and WDIOF_CARDRESET.
> 
> Besides, since alternating boot event is triggered by WDT SoC reset,
> it is classified as WDIOF_CARDRESET.
> 
> Signed-off-by: Chin-Ting Kuo <chin-ting_kuo at aspeedtech.com>
> ---
>   drivers/watchdog/aspeed_wdt.c | 83 ++++++++++++++++++++++++++++++++++-
>   1 file changed, 81 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
> index b4773a6aaf8c..4ad6335ff25b 100644
> --- a/drivers/watchdog/aspeed_wdt.c
> +++ b/drivers/watchdog/aspeed_wdt.c
> @@ -11,21 +11,31 @@
>   #include <linux/io.h>
>   #include <linux/kernel.h>
>   #include <linux/kstrtox.h>
> +#include <linux/mfd/syscon.h>
>   #include <linux/module.h>
>   #include <linux/of.h>
>   #include <linux/of_irq.h>
>   #include <linux/platform_device.h>
> +#include <linux/regmap.h>
>   #include <linux/watchdog.h>
>   
>   static bool nowayout = WATCHDOG_NOWAYOUT;
>   module_param(nowayout, bool, 0);
>   MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
>   				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> +struct aspeed_wdt_scu {
> +	const char *compatible;
> +	u32 reset_status_reg;
> +	u32 wdt_reset_mask;
> +	u32 wdt_sw_reset_mask;
> +	u32 wdt_reset_mask_shift;
> +};
>   
>   struct aspeed_wdt_config {
>   	u32 ext_pulse_width_mask;
>   	u32 irq_shift;
>   	u32 irq_mask;
> +	struct aspeed_wdt_scu scu;
>   };
>   
>   struct aspeed_wdt {
> @@ -39,18 +49,39 @@ static const struct aspeed_wdt_config ast2400_config = {
>   	.ext_pulse_width_mask = 0xff,
>   	.irq_shift = 0,
>   	.irq_mask = 0,
> +	.scu = {
> +		.compatible = "aspeed,ast2400-scu",
> +		.reset_status_reg = 0x3c,
> +		.wdt_reset_mask = 0x1,
> +		.wdt_sw_reset_mask = 0,
> +		.wdt_reset_mask_shift = 1,
> +	},
>   };
>   
>   static const struct aspeed_wdt_config ast2500_config = {
>   	.ext_pulse_width_mask = 0xfffff,
>   	.irq_shift = 12,
>   	.irq_mask = GENMASK(31, 12),
> +	.scu = {
> +		.compatible = "aspeed,ast2500-scu",
> +		.reset_status_reg = 0x3c,
> +		.wdt_reset_mask = 0x1,
> +		.wdt_sw_reset_mask = 0,
> +		.wdt_reset_mask_shift = 2,
> +	},
>   };
>   
>   static const struct aspeed_wdt_config ast2600_config = {
>   	.ext_pulse_width_mask = 0xfffff,
>   	.irq_shift = 0,
>   	.irq_mask = GENMASK(31, 10),
> +	.scu = {
> +		.compatible = "aspeed,ast2600-scu",
> +		.reset_status_reg = 0x74,
> +		.wdt_reset_mask = 0xf,
> +		.wdt_sw_reset_mask = 0x8,
> +		.wdt_reset_mask_shift = 16,
> +	},
>   };
>   
>   static const struct of_device_id aspeed_wdt_of_table[] = {
> @@ -213,6 +244,52 @@ static int aspeed_wdt_restart(struct watchdog_device *wdd,
>   	return 0;
>   }
>   
> +static int aspeed_wdt_update_bootstatus(struct platform_device *pdev,
> +					struct aspeed_wdt *wdt)
> +{
> +	struct resource *res;
> +	struct aspeed_wdt_scu scu = wdt->cfg->scu;
> +	struct regmap *scu_base;
> +	u32 reset_mask_width;
> +	u32 reset_mask_shift;
> +	u32 reg_size = 0;

Please no unnecesary initializations.

> +	u32 idx = 0;
> +	u32 status;
> +	int ret;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	reg_size = res->end - res->start;
> +
> +	if (reg_size != 0)
> +		idx = ((intptr_t)wdt->base & 0x00000fff) / reg_size;
> +
> +	/* On ast2400, only a bit is used to represent WDT reset */
> +	if (of_device_is_compatible(pdev->dev.of_node, "aspeed,ast2400-wdt"))
> +		idx = 0;
> +

There is some redundancy in the above code, and platform_get_resource()
can return NULL. If idx==0 for aspeed,ast2400-wdt anyway, the code can be
rewritten as

	if (!of_device_is_compatible(pdev->dev.of_node, "aspeed,ast2400-wdt")) {
		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
		if (res) {
			reg_size = res->end - res->start;
			if (reg_size)
				idx = ((intptr_t)wdt->base & 0x00000fff) / reg_size;
		}
	}

> +	scu_base = syscon_regmap_lookup_by_compatible(scu.compatible);
> +	if (IS_ERR(scu_base))
> +		return PTR_ERR(scu_base);
> +
> +	ret = regmap_read(scu_base, scu.reset_status_reg, &status);
> +	if (ret)
> +		return ret;

The above only affects bootstatus. Why fail to load the driver just because
bootstatus can not be read ?

> +
> +	reset_mask_width = hweight32(scu.wdt_reset_mask);
> +	reset_mask_shift = scu.wdt_reset_mask_shift +
> +			   reset_mask_width * idx;
> +
> +	if (status & (scu.wdt_sw_reset_mask << reset_mask_shift))
> +		wdt->wdd.bootstatus = WDIOF_EXTERN1;
> +	else if (status & (scu.wdt_reset_mask << reset_mask_shift))
> +		wdt->wdd.bootstatus = WDIOF_CARDRESET;
> +	else
> +		wdt->wdd.bootstatus = 0;

That is already 0.

> +
> +	return regmap_write(scu_base, scu.reset_status_reg,
> +			    scu.wdt_reset_mask << reset_mask_shift);
> +}
> +
>   /* access_cs0 shows if cs0 is accessible, hence the reverted bit */
>   static ssize_t access_cs0_show(struct device *dev,
>   			       struct device_attribute *attr, char *buf)
> @@ -458,10 +535,12 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
>   		writel(duration - 1, wdt->base + WDT_RESET_WIDTH);
>   	}
>   
> +	ret = aspeed_wdt_update_bootstatus(pdev, wdt);
> +	if (ret)
> +		return ret;
> +
>   	status = readl(wdt->base + WDT_TIMEOUT_STATUS);
>   	if (status & WDT_TIMEOUT_STATUS_BOOT_SECONDARY) {
> -		wdt->wdd.bootstatus = WDIOF_CARDRESET;
> -
>   		if (of_device_is_compatible(np, "aspeed,ast2400-wdt") ||
>   		    of_device_is_compatible(np, "aspeed,ast2500-wdt"))
>   			wdt->wdd.groups = bswitch_groups;